The primary objective of the proposed research project is to supplement the means by which chemotherapeutic agents may be screened for pharmacological activity and toxicity in small animals. The development of a simple, implantable infusion pump in our laboratories circumvents the difficulties previously encountered in small animal infusion screening, principally those involving percutaneous catheterization, pump miniaturization and animal restraint. To provide information as to the physiological activity of drugs under continuous infusion conditions, we propose to develop a method for continuous, low rate infusion of chemotherapeutic agents in small laboratory animals, to be used in drug screening programs at the level of the National Cancer Institute. The initial phase of the proposed project would consist primarily of design, development and in vitro testing of our infusion pump, appropriately miniaturized for rats and rabbits. Initial prototypes of this model have already been designed and built, and some preliminary testing accomplished. The final phase would be allocated for in vivo testing of the miniature pumps for optimal implantation sites and procedures, tissue compatibility studies, and in situ performance; flow rate constancy would be tested by sampling of blood and urine for a variety of infusates using inert and radioactively labelled compounds of varying metabolic activity as measurable infusate solutes. In summary, the specific objectives of the research program are: Modification of existing infusion pump technology for small animals use; Testing of resulting product for functional capability, in vitro and in vivo.